The quality of winter sports equipment intended for sliding, for example on snow, in particular of skis and snowboards, is determined to a large extent by their sliding properties. Therefore, such winter sports equipment has as a rule a sliding coating which is intended to improve the sliding properties of the equipment on snow. Such a sliding coating substantially comprises a sheet which is adhesively bonded to the skis or snowboards with the aid of suitable adhesives. Such a sliding coating should be as hydrophobic as possible in order to ensure good sliding.
Due to its excellent sliding properties over a very broad spectrum of different types of snow, first, low-pressure polyethylene has been used as the material for the sliding coating (CH-A 601394), but has problems with the mechanical strength and resistance to wear. These problems are solved by using ultra high molecular weight polyethylene (PE-UHMW), however coatings of PE-UHMW cannot be produced by extrusion, but have to be produced in expensive manner e.g. by pressing, sintering and subsequent peeling (CH-A 601394).
There is a series of proposals for solving these problems and improving the sliding coatings, for example by using a crosslinked polyethylene-based polymer obtainable by extrusion (CH-A 601394) or by the inclusion of water-soluble compounds in the sliding coating (CH-A 601392). A more recent development proposes a sliding coating comprising polytetrafluoroethylene (AT-B 394 951), which, however, is not very advantageous simply for cost reasons and moreover does not sufficiently solve the problems of the sliding coatings for winter sports equipment. None of these proposals have become established in practice, and modern skis and snowboards usually have a sliding coating comprising PE-UHMW, which, owing to the high crystallinity, has the highest mechanical and chemical stability of the polyethylenes. Originally, this polyethylene has been used for manufacturing hip joints in the medical technology and is processed in powder form like thermosetting plastics in pressing and sintering processes using customary antistatic agents and lubricants.
It is also known to improve the sliding properties of sliding coatings by applying a surface structure which further improves the hydrophobic properties of the coating. However, there is a difficulty in that the effect of the surface structure does no longer occur if the structure is damaged, for example by slight mechanical influences in the course of use.
The slidability of skis is also improved by using special waxes, which usually is still required even on skis provided with a sliding coating. The reason for the use of waxes is on the one hand that they improve the hydrophobic properties of the sliding coating, and on the other hand that polyethylene, like virtually all plastics, does not change its surface hardness in a temperature range from about +20 to −20° C., whereas the sliding properties of the snow change as a function of temperature. Accordingly, waxes which, through a very wide range of additives, are designed for the various temperatures and types of snow are used, wherein a harder surface is desired at lower snow temperatures and a softer surface is desired at higher snow temperatures. Moreover, waxes which, in addition to adjustment of the surface hardness also form nanostructures which give rise to a lotus effect and hence ensure a completely unwettable surface are also obtainable. However, the use of waxes is complicated and a correct choice of a wax is difficult. In practice, it is necessary to stock a plurality of waxes in order to be able to react appropriately to different snow conditions.
WO 2004/069352 discloses sliding coatings for winter sports equipment, which are based on a mixture of two different copolymers, wherein one of the copolymers presents a copolymer of propylene and at least one further olefin, which is composed at least of 50% of structural building blocks derived from propylene monomers, based on the total number of the structural building blocks, and the other copolymer presents a copolymer of ethylene and at least one further olefin containing at least 50% of structural building blocks derived from ethylene, based on the total number of the structural building blocks. The sliding coatings or winter sports equipment, respectively, described in WO 2004/069352, which have these sliding coatings, have already excellent characteristics, especially with respect to their slidability. However, the expert is greatly restricted with respect to the copolymer system to be used in manufacture of corresponding winter sports equipment with sliding coatings.
Therefore, there is a need for sliding coatings for winter sports equipment and for winter sports equipment having such sliding coatings, in which the sliding coating is constructed of other polymers or polymer mixtures, respectively, and which have at least equally good, however, preferably even better mechanical properties and especially sliding properties than the winter sports equipment or sliding coatings known from WO 2004/069352, respectively.